The present invention relates to an image recording apparatus for performing picture recording on both surfaces of recording paper, and particularly relates to a paper jam detecting device for detecting paper jam of the recording paper.
In such an image recording apparatus of the kind as described above, conventionally, when picture recording (copying) is performed on both surfaces of recording paper, as shown in FIG. 4, toner 14 of a developing portion 13 is made to adhere onto a photosensitive body 12 electrically charged by laser light generated from a laser generating portion 11 so as to form a toner latent image, the formed toner latent image is transferred by a transfer charger 19 onto recording paper 18 conveyed by conveyer rollers 16 and 17 from a paper feed tray 15 so as to perform picture recording on the recording paper, and the recording paper 18 on which picture recording is performed is once conveyed into a discharge tray 22 by a conveyer roller 20 and a forwards rotating discharge roller 21. After a predetermined time has passed (just before the recording paper 18 is discharged onto the discharge tray 22), the discharge roller 21 is reversely rotated so as to take the recording paper 18 into the apparatus again, and the conveying path is switched by a not-shown switching lever so that the recording paper 18 is conveyed by the conveyer roller 23 into a conveying path shown at the lower portion in the drawing so as to be taken into the paper feed tray 15 again. The one-surface copied recording paper 18 is then conveyed by the conveyer rollers 16 and 17 again so that picture recording is performed on the other surface of the recording paper 18, and the recording paper 18 is discharged into the discharge tray 22 by the conveyer roller 20 and the discharge roller 21 which are controlled so as to rotate forwards.
In the above picture recording apparatus, however, there has been a problem in that since recording paper to be subject to picture copying on its both surfaces is once conveyed into the discharge tray as described above in order to reduce the number of parts to make the apparatus small in size and light in weight, recording paper which has been already discharged in the discharge tray adheres onto the recording paper once conveyed on the discharge tray by static electricity induced on the conveyed recording paper so that the former recording paper follows the recording paper to be subject to both surface copying when the discharge roller is reversely rotated. Accordingly, the recording paper which has been already discharged in the discharge tray is sometimes taken into the picture recording apparatus to cause paper jam in the apparatus.